Rotary piston engine

ABSTRACT

A non-reciprocating engine comprising a hollow cylindrical shaft driver ( 13 ) located in a cylindrical stator cavity ( 14 ) of a stator. A number of expansion chambers ( 43 ) form between the outer wall of the shaft driver, the stator wall and movable dividers ( 25 ) which extend from the stator to bear on the shaft driver. The expansion chambers expand and contract during operation of the engine. An output shaft passes centrally through the stator cavity and shaft driver and has offset bearings ( 34 ) which bear on the inside surface of the shaft driver. Inlet ports in a removable inlet end plate of the stator allow pressurised air or air/fuel mixture, for example, to be introduced into the expansion chambers. Sequential expansion and contraction of the chambers around the circumference of the shaft driver causes a combination of orbital and rotational movement of the shaft driver and consequential rotation of the output shaft. The shaft driver rotates at only a fraction of the speed of rotation of the output shaft (in the order of {fraction (1/10)} th -{fraction (1/20)} th  the speed of rotation of the output shaft). One orbit of the shaft driver is equivalent to one rotation of the output shaft.

The present invention relates to motors or engines and more particularlyto a crankless engine which may be in the form of an internal combustionengine, a fluid driven motor such as an air motor, or a steam drivenengine.

The term “crankless” refers to the fact that the motor does not have aconventional crankshaft and is not subject to reciprocating motion. Theoutput shaft of the engine is in fact a straight shaft which is causedto rotate by offset bearings located in a drive member which may betermed a shaft driver, although in the strict sense, the motion of theso-called shaft driver is more an orbital motion with slow rotationrelative to the speed of rotation of the output shaft.

Many different forms of rotary and orbital engines as well as otherforms of engines have been proposed in the past with varying degrees ofsuccess but overall there has been no serious challenge to thereciprocating internal combustion engine at least insofar as automobilesare concerned. This fact is primarily due to the high wear rate inrotary engines and possibly the fact that the improvements in efficiencyof rotary engines over reciprocating engines has not been sufficient tojustify a major change in direction for engine manufacturers.

It is an object of this invention to provide an alternative form of anon-reciprocating type motor or engine which overcomes one or more ofthe shortcomings of prior art engines.

Accordingly the invention provides an engine comprising a hollowcylindrical shaft driver located in a stator cavity of the engine andsurrounded by expansion chambers defined between the cylindrical wall ofthe shaft driver and the wall of the stator cavity, said expansionchambers being separated by movable dividers mounted in said stator andbearing on said shaft driver, an output shaft rotatably supported insaid stator and passing centrally through said stator cavity and throughsaid shaft driver, said shaft having bearing means to one side of saidshaft which bear on the inside surface of said shaft driver whereby acombination of orbital and rotational movement of said shaft drivercauses rotation of said shaft at a rotational speed much greater thanthe rotational speed of said shaft driver.

In order that the invention may be more readily understood oneparticular embodiment will now be described with reference to theaccompanying drawings which show an air driven engine. In the drawings:

FIG. 1 is a perspective view from the inner side of an inlet end plateand inlet manifold of the engine;

FIG. 2 is a perspective view, from the outside, of a stator of theengine and shows, in exploded view, a shaft driver and movable dividersof the engine;

FIG. 3 is a perspective view of an output shaft assembly of the engine;

FIG. 4 is an end view of the engine from the inlet manifold end;

FIG. 5 is a view similar to FIG. 4 with inlet end plate and output shaftremoved;

FIG. 6 is an end view of the output shaft assembly;

FIG. 7 is a perspective view (partly exploded view) from the outer sideof the inlet end plate and inlet manifold;

FIG. 8 is a perspective view, from the inside, of the stator, shaftdriver, and movable dividers, in an exploded view;

FIG. 9 is a further perspective view (from the opposite end to FIG. 3)of the output shaft assembly;

FIG. 10 is similar to FIG. 4 with end cap removed;

FIG. 11 is an end view of the engine from the output end with outputshaft removed;

FIG. 12 is an end view of the engine end plate with inlet manifold andend cap removed;

FIG. 13 is an enlarged perspective view of a timing member located atthe inner end of the output shaft; and

FIGS. 14(i)-(iv) show a cycle of the shaft driver within the statorcavity to produce a single revolution of the output shaft.

In the drawings, the engine is shown to comprise essentially a stator10, an inlet end plate 11 and a output shaft 12. A shaft driver 13 is ahollow cylindrical ring which, when the engine is assembled, is locatedin a cylindrical stator cavity 14 of the stator 10.

The inlet end plate 11 has an inlet manifold 15 mounted centrally on theouter end thereof and a removable end cap 16 provides an air intake 17to the inlet manifold 15. The inlet manifold 15 (see FIG. 7) fits over acylindrical boss 45 of the end plate 11 and is locked onto the boss 45by grub screws (not shown). The rotational position of the manifold 15relative to the boss 45 may be adjusted to vary the timing of theengine. As is evident flexible pressure hoses 18 extend from the inletmanifold to inlet ports 19 in the end plate 11. The interior of the endcap 16 communicates with ports 20 (see FIG. 7), each of whichcommunicates with one of the pressure hoses 18 to distribute inlet airat air intake 17 to the respective inlet ports 19 via the pressure hoses18. The ports 20 are opened or closed by a timing member 36 locked tothe inner end of output shaft 12 as will be described hereinafter. Theend cap 16 is fixed to the inlet manifold 15 by bolts 21 which extendaxially and enable the end cap 16 to be clamped firmly to the inletmanifold 15 in an airtight arrangement. A roller bearing 22 is locatedin the end plate 11 to support the output shaft 12.

As is more evidence in FIGS. 5 and 8, the stator 10 has a cylindricalstator 14 which is larger in diameter than the diameter of the shaftdriver 13. The wall 23 of the stator 10 has part cylindrical grooves 24which extend arcuately from a point in the stator cavity through thewall 23 and back to the stator cavity at a circumferentially displacedlocation. These grooves 24 accommodate respective movable dividers 25which are able to move in the respective grooves 24 whereby an edge of amoveable divider 25 bears on the outer surface of the shaft driver 13.As is evident in FIG. 8 for example, the movable dividers 25 are partcylindrical dividers with a end portion 26 which supports an axial shaft27 on which the divider pivots. The axial shaft 27 extends through ahole 46 in the stator 10 and passes out the end of the stator. As can beseen more clearly in FIG. 11, a spiral spring 28 locates in a slot inthe end of each axial shaft 27 and is fixed to the stator 10 in order tobias pivotal movement of the respective moveable divider in a mannerwhereby an edge of the divider bears on the shaft driver 13. A furtherroller bearing 29 is located in the stator to support the output shaft12. As is apparent in the drawings, holes 30 in the stator 10 andcorresponding holes 31 in the end plate 11 enable the two parts to bebolted together in sealing engagement by bolts (not shown).

As is evident in FIGS. 5 and 11, exhaust ports 32 extend from thecylindrical stator cavity 14 through the fixed end of the stator 10 toallow exhaust air to dissipate to atmosphere. In addition to theseexhaust ports 32, which allow primary exhaust air to dissipate at theopposite end of the stator 10 to the inlet manifold 15, a further orsecondary exhaust route is provided via the inlet ports 19 and the inletmanifold 15. The secondary exhaust route follows the inlet air path backto the start of the ports 20 and a timing member or disc member 36.(FIG. 13) which bears on the outer surface 39 (FIG. 10) of the inletmanifold 15. A recessed portion 37 of the timing or disc member 36allows one of the ports 20 to communicate with the bore of the timingdisc 36. The bore of the timing or disc member 36 is a clearance fitover output shaft 12 (creating space 40) and thus any exhaust air forcedback via the inlet manifold to timing or disc member 36 is capturedwithin the recessed portion 37 and forced into space 40. As radial hole47 in the inlet manifold extend to the space 40 and provides an exhaustoutlet for this secondary exhaust air.

The output shaft 12 consists essentially of a straight shaft that ismounted in the roller bearings 22 and 29 of the inlet end plate 11 andstator 10, respectively. A driven plate 33 is mounted on the shaft andin the assembled engine locates within the shaft driver 13. The drivenplate 33 has mounted thereon a pair of roller bearings 34 which areclosely adjacent to each other and to one side of the shaft. The rollerbearings 34 bear on the inside wall of the shaft driver 13 and aredriven around the inner perimeter of the shaft driver 13 as will becomeapparent hereinbelow. The driven plate 33 is arranged to be rotationallybalanced with the roller bearings 34. At the inner end of the shaft 12 anut 35 retains the timing disc 36 on the shaft. The timing or discmember 36 has recessed portion 37 in a surface 38 of the timing or discmember 36 which bears on the outer surface 39 of the inlet manifold 15.As is evident in FIG. 10, the manifold 15 fits over the output shaft 12and a space 40 exists therebetween. The recessed portion 37 as it movesaround on the outer surface 39 exposes the ports 20 to the space betweenthe inlet manifold and the shaft. The previously described radial hole47 in the inlet manifold communicates with the space 40 and enablesfurther exhausting of air in an expansion chamber of the engine as willbecome apparent hereinbelow.

A cut-out portion 42 in the circumference of the timing or disc member36 exposes the ports 20 to inlet air pressure from the air intake 17.The timing or disc member 36 is therefore responsible for timingfunctions related to inlet air pressure and secondary exhaust air fromthe expansion chambers.

As will be evident in FIG. 5 and FIG. 14, expansion chambers 43 of theengine are formed between the outer surface of the shaft driver 13, thesurface of the stator cavity 14 and between the dividers 25 where theycontact the surface of the shaft driver 13. These expansion chambers 43take varying shapes as the shaft driver 13 moves within the statorcavity 14. In order to better understand this movement, reference shouldnow be made to FIG. 14 which shows a cycle of the engine resulting in acomplete revolution of the output shaft 12. The engine is driven in thisembodiment by compressed air and air under pressure is thereforeconnected to air intake 17 on the end cap 16. A suitable valve (notshown) is provided in order to open the supply of compressed air.

In FIG. 14, the four expansion chambers are labelled (a), (b), (c) and(d) for convenience in explaining a cycle of operation. Referring toFIG. 14(i), the expansion chamber 43(a) is receiving pressurised airbecause the timing member 36 is positioned on the end of the inletmanifold so as to expose the relevant port 20 to the pressurised air.Pressure in expansion chamber 43(a) creates a force against the side ofthe shaft driver 13 causing it to move in a direction whereby itscontact with the surface of stator cavity 14 moves in an anti-clockwisedirection. In other words, the shaft driver 13 does not specificallyrotate but moves in a type of motion whereby the point or surfacecontact between it and the stator cavity 14 moves around thecircumference of the stator cavity 14. Further expansion of the chamber43(a) causes the shaft driver 13 to assume a position as shown in FIG.14(ii) and at this point in time, the shaft has rotated through 90° asshown by the position of the roller bearings 34 which are forced toremain in a space available internally in the shaft driver 13 by virtueof its offset position relative to the axes of the output shaft 12. Thisrotation of the output shaft 12 through 90° causes the timing member 36to expose the next relevant port 20 to high pressure air which thenenters the expansion chamber 43(b) further pushing the shaft driver 13around within the stator cavity 14.

It should be mentioned at this time that whilst the movable dividers arespring biased so that an edge thereof remains in contact with the outersurface of the shaft driver 13, pressure in an expansion chamber alsoacts via arcuate grooves 24 on the edge of the divider 25 not in contactwith the shaft driver 13, to thereby assist in applying pressure betweenthe divider and shaft driver.

Referring now to FIG. 14(iii), it can be seen that the cycle continuesand in the position shown in FIG. 14(iii), the shaft has rotated 180°.In this position, compressed air is being received in expansion chamber43(c) whilst chambers 43(a) and 43(b) have been fully expanded. Itshould be noted that movement of the shaft driver 13 has exposed exhaustport 32 in chamber 43(a) whereby subsequent contraction of the chamber43(a) by further movement of the shaft driver allows some of the air inchamber 43(a) to exhaust via the exhaust port 32.

As shown in FIG. 14(iv), the shaft driver 13 has moved to a new positionwhereby the output shaft 12 has rotated through 270° from the initialposition. In this position, the exhaust port 32 shown in FIG. 14(iii)has been closed by the movement of the shaft driver 13 but the chamber43(a) is still contracting. This contraction of chamber 43(a) wouldcompress air in that chamber if there was no other means for the air toescape. Such means is provided by the previously described secondaryexhaust route. This enables air to return via the appropriate inlet port20, into the recessed portion 37 of the timing member 36 and then intothe space 40 between the inlet manifold and output shaft to eventuallyexit via exhaust port or radial hole 47. This means that the expansionchamber 43(a) can continue to contract in size as is evident in FIGS.14(iii) and 14(iv) without compressing air in that chamber and resistingsuch movement. Similar events occur as the other chambers contract. Inthe next step of the cycle the components resume the position shown inFIG. 14(i).

As will be evident from the above description, the shaft driver 13 movesin the stator cavity 14 whereby contact between the outer circumferenceof the shaft driver 13 and the surface of stator cavity 14 moves aroundthe cavity 14 as each expansion chamber receives compressed air. Thismovement may be considered as a type of orbital movement and whilst theshaft driver 13 does not rotate at the same speed as the output shaft12, there is some rotation of the shaft driver 13. The speed of rotationof the shaft driver 13 depends upon the difference in circumferencebetween the shaft driver and the stator cavity 14. Generally speaking,the shaft driver 13 rotates at a speed of about {fraction (1/12)}^(th)to {fraction (1/20)}^(th) of the speed of rotation of the output shaft12. This provides a distinct advantage in that there is minimal wearbetween the surface of the movable dividers 25 where they contact theshaft driver 13 and the surface of the shaft driver 13. This is becausethere is little rotation of the shaft driver 13 relative to the outputshaft 12. As will also be evident, rotation of the output shaft 12 iscaused by the roller bearings 34 moving, or remaining, in the spaceprovided for them within the shaft driver 13.

The direction of rotation of the output shaft 12 is simply reversed byrotating the manifold 15 on the cylindrical boss 45. The rotation of themanifold will expose next port 20 to the cut-out portion 42 in thecircumference of the timing member 36 to communicate the interior of theend cap 16 with chamber 43(b) instead of chamber 43(a) as per FIG.14(i).

Whilst the embodiment described above relates to an engine driven bycompressed air, clearly other types of engines may be readilyconstructed. For example, by providing spark plugs in the stator cavity14 for each expansion chamber and introducing a fuel/air mixture intothe engine, an internal combustion engine may be provided. Also, theengine could be driven by steam or by other fluid means. It is alsoconceivable that an internal combustion engine embodiment of theinvention could drive a vehicle as well as an air compressor in thevehicle whereby during certain times, the fuel air mixture could beturned off and the engine could run from compressed air provided by thecompressor. This would have advantages where fuel is not available orwhere pollution by internal combustion engine exhaust is a sensitiveissue. For example, within certain city limits internal combustionengines may be prevented from use in the future and an engine of thetype described herein could be run on compressed air for periods of timewhilst in these areas.

It should be apparent that the engine according to the present inventionoffers many advantages over existing engines. For example, the engine isnon-reciprocating and therefore is essentially vibration free. There arefewer moving parts and minimum friction resulting in a much moreefficient engine with minimum wear. The output shaft of the engine is astraight shaft and therefore avoids many of the inherent balancing andvibration problems of existing reciprocating engines. In order toincrease the output power of the engine according to this invention, itis merely necessary to provide additional stator assemblies on the sameoutput shaft. The engine is compact and lighter than existing enginesand this results in improved efficiency.

Whilst one particular embodiment has been described in detail, it shouldbe evident to persons skilled in the art that variations may be readilyeffected without departing from the spirit and scope of the invention.Clearly additional parts can be added to provide a production version ofthe engine. For example, it would be necessary to provide an outletmanifold covering the exhaust ports 32 in order to direct the exhaustair to a single exhaust outlet point. Also, a fly-wheel (not shown)would be provided in order to contribute to the smoother running of theengine.

1. An engine comprising a shaft driver located in a stator cavity of theengine and surrounded by expansion chambers defined between a wall ofthe shaft driver and the wall of the stator cavity, characterized inthat, said shaft driver is a hollow cylinder, and said expansionchambers are separated by movable dividers mounted in said stator andbearing on said shaft driver, an output shaft is rotatably supported insaid stator passes centrally through said stator cavity and through saidshaft driver and said output shaft has bearing means to one side of saidoutput shaft which bear on the inside surface of said shaft driver, saidshaft driver bearing on said stator wall at a circumferential pointextending along the length of the cylindrical wall of the shaft driverand said circumferential point moves around the wall of said statorduring said orbital and rotational movement, whereby one revolution ofsaid circumferential point around said stator wall is equivalent to onerevolution of said output shaft, and during said one revolution of saidshaft driver rotates about its own axis only a small fraction of arevolution, and whereby a combination of orbital and rotational movementof said shaft driver causes rotation of said output shaft at arotational speed much greater than the rotational speed of said shaftdriver.
 2. The engine as defined in claim 1, characterized in that, saidsmall fraction of a revolution is about {fraction (1/10)}^(th) of arevolution or less.
 3. The engine as defined in claim 1 characterized inthat, said small fraction of revolution is between {fraction(1/10)}^(th) and {fraction (1/20)}^(th) of a revolution.
 4. The engineas defined in claims 2 and 3, characterized in that, said movabledividers comprise part cylindrical dividers which pivot on a centralaxial shaft of the divider, the part cylindrical wall of each dividerbeing located in an arcuate groove in the stator whereby pivotalmovement of a divider causes an edge of said cylindrical wall to bear onsaid shaft driver to thereby define one extremity of said expansionchamber.
 5. The engine as defined in claim 4, characterized in that thewall of said stator cavity is cylindrical and extends between an endwall of said stator at one end, and a removable inlet end plate at theother end, and said arcuate grooves and said dividers extend the lengthof said stator cavity.
 6. The engine as defined in claim 5,characterized in that, said bearing means comprise a pair of rollerbearings mounted on a disc locked to said shaft.
 7. The engine asdefined in claim 6, characterized in that said removable end plate hasinlet ports to the respective expansion chambers and said end wall ofsaid stator has outlet or exhaust ports.
 8. The engine as defined inclaim 7, characterized in that, said movable dividers are spring biasedto pivot such that said edge remains in contact with said shaft driver.9. The engine as defined in claim 8, characterized in that, an inletmanifold is mounted to said removable end plate for directing inlet airto said inlet ports.
 10. The engine as defined in claim 9, characterizedin that, said inlet manifold also provides for egress of some exhaustair flow.
 11. The engine as defined in claim 10, characterized in that,a timing member is mounted onto an inner end of said output shaft torotate with said output shaft, said timing member selectively coveringsaid inlet ports during rotation to control inlet airflow to saidengine.